1. Field of the Invention
The present invention generally relates to a cordless modem and, more particularly, to a high-speed, cordless data/facsimile modem wirelessly connecting a portable computer modem to a nearby telephone jack.
2. Description of the Related Art
Cordless telephones are popular consumer items which are now found in many homes. Cordless telephones comprise a base unit connected to a standard telephone wall jack and a portable handset connected via a radio link to the base unit. The portable handset is used for talking, listening, dialing, and ringing, and the base unit is used to interface between the radio link and the telephone network. In operation, the user is free to converse on the telephone while roaming around the house, yard, or office, in the general vicinity of the base unit without being encumbered by a cord.
Due to the scarcity of usable spectrum, many countries regulate bandwidth and transmission power of radio communications. In the U.S., the Federal communications Commission (FCC) has limited cordless telephones to a maximum power in the 900 MHZ ISM band. Under current power and spectrum constraints, roaming range is about one thousand feet from the base unit. Beyond that distance, the radio signal fades and quality degrades.
Many homes and offices are also equipped with personal computers (PCs), most of which include a modem to facilitate data communications to other computers via standard telephone lines. A modem converts and compresses a high-speed, digital, serial data stream from a computer into a complex analog modulated signal that can be carried over standard telephone lines. Present modem technology makes it possible to send data streams as fast as 33.6 and 56 kbps over the telephone network. Modern modems and modem software enable the modem to perform additional functions such as the ability to send and receive facsimile data. Modems with facsimile capabilities are typically referred to simply as data/fax modems.
Standard PCs, are typically situated at fixed location, such as a desk-top, and not moved very often. The PC's modem, either internal or external to the PC, is physically connected to a standard modular telephone wall jack via a telephone cord. Hence, the user is required to operate the computer in the proximity of the wall jack since the modem is physically tied to the wall and these jacks are often not located in convenient places. Cord connections work well for most desk-top PCs installations without many drawbacks, except that perhaps a telephone wall jack may need to be installed closer to the PC so as to avoid running a long extension cord around the room. Telephone cords are, however, undesirable for portable or mobile computers, such as, for example, lap-tops, palm-tops, and notebooks, which enable computing anytime, anywhere.
Hence, it would be desirable to have a cordless modem to permit a laptop computer connected to a modem to roam from room to room similar to the way one roams with a cordless telephone handset. Unfortunately, conversational voice data and computer modem data have different bandwidth, signal fidelity requirements, and security requirements. Therefore, one cannot simply connect a modem to a cordless telephone.